Stereotype mat



Patented o r, 14,-1930 ETD A'T'Es ARI-IE W. SCHORGER, OF -MADISON,WISCONSIN, ASSIGNOR TO G. F. BURGESS LABORA- TORIES, INQ,01EMADISON,-WISCOI TSI1\T, A CORPORATION OF DELAWARE PATENT OFFICEs'rnanoryrn MAT No Drawing.

7 This invention relates to an improvement in sterotype mats andespecially the so-called' dry mats of commerce.

; Stereotype mats and especially dry mats consist of a heavyfibroussheet, usually comprising chemical wood pulp, and containing suitablefillers. Such a .mat and the method of making is described in UnitedStates Patent No. 1,524,155. Thesesheets usually vary from 0.028 inch to0.036 inch in thickness. Their physical characteristics may vary fromsoft to hard depending upon the requirements of the user. A facingmaterial or coating may be applied to the surface of the mat that comesin contact with the type and stereotype metal to improve the release ofthe hot metal and improve the qualityof the printing.

A stereotype mat for newspaper work is used in the following manner. Assoon as a form containing the type has been set up, a stereotype mat issuperimposed, then covered with blankets or felts and passed through arolling machine, whereby the mat acquires a reverse impression of thetype. The mat 'after drying .is placed in a casting machine where it isheld in the form of a cylinder. Molten stereotype metal is then pouredinto the machine whereby a stereotype plate in the form of a metalcylinder is obtained containing on its surface an exact duplicate of thetype in the original flat form.

The stereotype plate is then placed in a cylinder press whereby paperscan be printed at high speed. Several casts can be made easily andrapidly from the same mat so that a number of presses can be placed inoperation almost simultaneously.

A dry mat is not used in the dry state. It is first placed in a humidorwhere it takes up from 10 to 30 per cent moisture. It is then rolled ona form, removed, placed in a cylindrical scorcher where most of themoisture is removed in one or two minutes. When the hot stereotype metalstrikes the impressed 7 scorched surface practically all of the balanceof the moisture is driven out of the mat. As a result of such strenuoustreatments various troubles are encountered. It is the object of myinvention to overcome or minimize these troubles.

Application filed April 26, 1929. Serial No. 358,424.

heretofore encountered in its use, disappear.

These punctures should not cut the fibers but merely push'them asideduring the piercing operation; hence the strength of the mat is notaffected materially. I have found that a mat punctured to within 0.006ofthe face of the mat gives excellent results. It is preferable to havethe holes spaced apart not more than in each direction. This spacing canbe advantageously much less, giving ex cellent results. The exactspacing and depth of puncture will vary with the type of mat and serviceto which it is to be put. Puncturing the mat in this manner results inseveral advantages over mats heretofore used. These advantages are: i

1. 1 The mat can be scorched (dried) more quickly;

2. The formation of steam pockets by blistering is prevented;

3. Relief'of stresses in the mat, and consequent reduction, ifnot'elimination, of buckling is obtained;

4. Increased flexibility is obtained;

5. Chilling in the sterotyped plates is reduced.

The above mentioned advantages will be ance to the escape of the steam,and this may a result in splitting the mat or producing blisters. Steamcan escape in the longitudinal direction ofthe mat, that is in the fiberdirection, more easily than it can perpendicularly. As a result of theperforations inch apart, it is not necessary for the steam to travelmore than inch before it has an 2. Blistering occurs most frequently on.

cuts representing objects. A large continuous area of the mat repre'"sei'ited bythe cutisa compressed greatly, frequently to one-half theoriginal thicknessofthe heat. The moisture leaves" this area much moreslowly during' scorching than other" parts of themat. If the cuts retainsome moisture due to incomplete drying, blisters will be formed when thehot stereotype metal is poured againstthem. The perforations helpeliminate this difficulty to a verygreat extent.

3. Buckling may be largely eliminated through release or'avoidance ofstressesin the All mats, particularly the dense type, have certainstresses produced'in the course of manufacture. The more frequentcauseo'f stresses and buckling, is uneven drying; If a'portionofthe matdries readily it will become se't as soon as allthe moisture hasescaped; As" a result the parts drying subsequently cause" high tensionand result inbuckling'l" Q 4. Perforation ofthe mats produces'acer I i:

tain"flexibility that permits better molding.

5. Perforation of the mat prevents chilling by permitting a'ir andste'am to escape The face of a chilled plate has", ripple marks as"though throughrthe back of the mat;

caused by ther'ushof air or steam through the molten metal. ture maychill the casting, but trouble'is' seldom encountered except on cutswhere the mat is very dense. Whenthe molten metal is poured into'jthebox, air; and steam must escape to a certain 'eXtent'through' the mat,

though mostis forced out at the top. The" minute points in cuts mayentra'p both air and steam and cause blowing unlessthey do escapethrough'the mat.;-

"I claim:

1'. A'stereotype mat havin'gamultiplicity of puncturesexten'dingfrom'theback-thereof toward the surface of themat- 2. Astereotype mat having afmultiplicity of punctures in the back thereof,most of said punctures extending to within at least 0.006

inch of'the opposite face ofsaidmat;

3. v A stereotype mat having a multiplicity of punctures inthe'backthereof but not extending. throughsaid'mat, said punctures be mgspaced not more than g" apart.

4'. A faced'stereotype mat having a mulas per- Any mat retainingmoistiplicity of punctures in the back thereof, most of said puncturesextendingto within at least 0.006 inch of the facing and said puncturesbeing spaced not more than 1 g apart. v

a 5. The step in the method ofventing steam from the back of; stereotypemats? during the casting operation which eamprises" piercing't'heba'c'ks of said mats with a multiplicity of punctures deep en oughto approachathe'ca'sta ingfaceof,;said mat.i-

In testimony whereof I affix my signature. ARLIE W. SCHORGER.

